Summary The aircraft departed Abbotsford International Airport at 1853 Pacific daylight time, under visual meteorological conditions, for the sixth flight of the day, and proceeded to uncontrolled airspace about 15 nm north of Abbotsford. There were two pilots and two company flight test engineers on board. A certification flight testing program was being conducted by Cascade Aerospace Inc. with the Bombardier DHC-8-402 (registration C-FBAM, serial number4040) modified for air tanker operations. At about 1930 Pacific daylight time, during a rate-one turn in cruise flight at 4500feet, the No.1 engine (PW150A, serial number PCE-FA0020) shut down without warning. The auto-feather system was disarmed, in accordance with normal procedures, and the alternate feather system was used to complete feathering of the propeller. The flight returned to Abbotsford at 1950 Pacific daylight time with one engine inoperative. Ce rapport est galement disponible en franais. Other Factual Information Operation The aircraft was being operated under the authority of a Transport Canada (TC) Flight Permit - Experimental. At the time of the incident, the Q400Airtanker conversion of the initial Bombardier DHC-8-400 design was undergoing supplemental type certificate (STC) certification flight testing for the fire-fighting role. The conversion included the installation of a 10000litre retardant delivery system. The pilot crew was employed by the Conair Group Inc. Both pilots had completed the Dash8 Q-400 initial pilot course at the Flight Safety International Toronto Learning Centre in November2004. Flight Recorders The aircraft was equipped with a Honeywell solid-state cockpit voice recorder (CVR) and an Allied Signal solid-state flight data recorder (FDR). Information was recovered from the FDR but not from the CVR. The pertinent information from the CVR was overwritten while external electrical power was applied to the aircraft following the incident flight. Powerplants The PW150A engine consists of a free-turbine turbo machine (TM) module driving a Dowty Aerospace modelR408 six-bladed propeller through a two-stage reduction gearbox (RG) module. The TM module includes the low-pressure (LP) compressor and its LP turbine, the single-stage centrifugal high-pressure (HP) compressor and its HP turbine, and the two-stage power turbine (PT) and its PT shaft, which drives the RG module. The three rotating assemblies are not connected together and rotate at different speeds and in opposite directions. The LP compressor case houses the LP compressor, an integral oil tank at the bottom, and an accessory gearbox (AGB) at the top. The AGB is driven by the HP turbine shaft through a vertical tower shaft and angle gearbox. The AGB drives the fuel metering unit (which incorporates the fuel pump), the starter/generator, and other accessories. Maintenance and Aircraft Records Aircraft records indicate that the left engine, serial number (s/n) PCE-FA0020, had about 1978flight hours of total time since new (TTSN) and that the right engine, s/n PCE-FA0015, had about 2016flight hours of TTSN. In summary, the engine logs for the incident engine (s/nPCE-FA0020) recorded about 1874hours in the first 19months after manufacture and about 104hours in the following 35months. It had not been operated for two extended periods. From October2003 until June2004, the aircraft was stored at the Bombardier West Virginia Air Center, and from October2004 to May2005, it was undergoing the air tanker conversion at Cascade Aerospace Inc. facilities. A copy of the Engine Service and Maintenance Record contains a Bombardier Maintenance Work Card from the West Virginia Air Center dated 30October2003. The work card contains an instruction to perform weekly engine idle runs in accordance with DHC-8 Q-400 aircraft maintenance manual (AMM) Chapter71-00-00. A single entry on that sheet dated 01May2004 recorded that this instruction had been complied with. A Cascade Aerospace Inc. non-routine maintenance card, dated 24November2004, contained a requirement to carry out an AMM task regarding preparation of the aircraft for storage of 91to 180days, including suggested action of weekly and monthly recurring inspections. The Corrective Action section of the maintenance card stated that the aircraft was prepared for storage and returned to service in accordance with the applicable AMM tasks, dated 14May2005. Additional worksheets recorded that weekly inspections were completed between 19January and 16February2005. On 22February2005, preparation of the aircraft for return to service commenced and was completed on 14 May 2005. TSB Engineering, Research, and Other Reports This occurrence is recorded as file CF 20050621013 in TC's service difficulty reporting (SDR) database. A search of TC's SDR database did not produce any similar occurrences in Canada or the United States. At this time, the only civilian aircraft equipped with the PW150A engine is the DHC-8-400 model. The TSB Engineering Laboratory participated in the engine teardown and produced report LP065/2005. Pratt & Whitney Canada (P) also produced an investigation report. Both reports presented the same information, but the P report also included the metallurgical analysis that was completed at P facilities. The reports noted that the No.30 bearing had significantly deteriorated and fractured into multiple pieces. All eight balls, portions of the bearing's outer race, and portions of the bearing cage were found in the oil pump, scavenge oil screen, the scavenge oil tube, and the blow-down housing for the cavity containing the No.3 and the No.4 bearing. The No.4 bearing is the thrust bearing for the HPcompressor shaft. Portions of the bearing were also found on the AGB chip detector and the two magnetic speed sensors for the HP compressor rotor. Localized corrosion-related pitting and staining was noted on the No.4 bearing balls, and inner and outer races, with the heaviest concentration at the six o'clock position. At the top of the tower shaft, localized rust-like stains were noted on the upper surface of the No.29 bearing rollers and outer cage, the lower surface of the oil shield, and the outer surface of the shaft portion of the spiral bevel gear. The teeth on the spiral bevel gear (bottom of tower shaft adjacent to the No.30 bearing) were smeared with metal, forced in the direction of rotation. Some of the teeth had fractured near the crown. The TSB Engineering Laboratory report concluded that: It is likely that the corrosion pitting noted on the left engine's No. 4, No. 29 and No. 30 bearing components was due to the bearings being stationary while in the presence of moisture. It is likely that the No.30 bearing failed due to corrosion pitting. The left engine flamed out because the AGB was not driving the fuel pump. Additional Information A chip detector fault code for the No. 1 engine TM module was recorded by the engine monitoring unit (EMU) at a time of 1559 on 15June2005, which coincided with the completion time of the third flight of the day. A fault code interrogation had been completed at the end of the previous day's flying with no faults detected. The next fault code interrogation was planned for the completion of the current day's flights. There is no chip warning or detection system available to the flight crew, although operators could make this information available to flight crews if they wish to. The No.30 bearing failure occurred about two hours of air time following the chip detector fault. During the time that engine s/nPCE-FA0020 was inoperative at Cascade Aerospace Inc. facilities, it remained on aircraft s/n 4040 along with engine s/n PCE-FA0015. Since both engines were stored under the same conditions, engine s/nPCE-FA0015 was also subjected to a preliminary inspection in the presence of TSB investigators at P (without complete disassembly) for indications of corrosion in the AGBdrive train area. The main and scavenge oil filters, main oil pump sump screen, engine oil sample, HPcompressor rotor speed sensors, and the TMchip detector were visually examined with no irregularities noted. The cover of the angle drive gearbox was removed to expose the No.29 bearing. The bearing itself could not be viewed due to the bearing/gear oil shield installation. However, nothing abnormal was observed as far as could be seen. P later completely rebuilt this engine and no anomalies were reported to theTSB. During the time that aircraft s/n4040 was not in service at the West Virginia Air Center, it was equipped with engines s/nPCE-FA0020 and s/nPCE-FA0063. The No.2 engine, s/nPCE-FA0063, was removed on 06June2004 and engine s/nPCE-FA0015 was installed in the No.2 position on the same date. The condition of engine s/nPCE-FA0063 was given consideration for comparison. However, the engine was viewed as a serviceable engine (as s/nPCE-FA0015 had been) and neither a teardown nor inspection was completed. Engine s/nPCE-FA0063 was subsequently installed on aircraft s/n4040 on 18June2005 and has since accumulated numerous hours without difficulties. Also during the period that the aircraft was at the West Virginia Air Center, the No.1 engine, s/nPCE-FA0020, was removed and sent to P facilities where it underwent a hot section inspection and other repair work between February and May2004. Part of the repair work included removal of the AGBcover plate enclosing the No.29 bearing. It could not be determined how long the access cover may have been left off or if it could have been re-installed without its preformed packing during that period. During that period, roof leaks were experienced at the P Service Center in the area where the subject engine had been worked on.